The Rho GTPases organize the actin cytoskeleton and are involved in cancer metastasis. Previously, we demonstrated that RhoC GTPase was required for PC-3 prostate cancer cell invasion. Targeted down-regulation of RhoC led to sustained activation of Rac1 GTPase and morphological, molecular and phenotypic changes reminiscent of epithelial to mesenchymal transition. We also reported that Rac1 is required for PC-3 cell diapedesis across a bone marrow endothelial cell layer. In the current study, we queried whether Rac3 and RhoG GTPases also have a role in prostate tumor cell diapedesis. Using specific siRNAs we demonstrate roles for each protein in PC-3 and C4-2 cell adhesion and diapedesis. We have shown that the chemokine CCL2 induces tumor cell diapedesis via Rac1 activation. Here we find that RhoG partially contributes to CCL2-induced tumor cell diapedesis. We also find that Rac1 GTPase mediates tight binding of prostate cancer cells to bone marrow endothelial cells and promotes retraction of endothelial cells required for tumor cell diapedesis. Finally, Rac1 leads to β1 integrin activation, suggesting a mechanism that Rac1 can mediate tight binding with endothelial cells. Together, our data suggest that Rac1 GTPase is key mediator of prostate cancer cell-bone marrow endothelial cell interactions.
Background Despite multiple randomized trials, the role of perioperative chemotherapy in colorectal cancer liver metastasis (CRLM) is still under debate. In this systematic review and network meta-analysis (NMA), we aim to evaluate the efficacy of perioperative systemic therapies for patients with CRLM. Methods We searched various databases for abstracts and full-text articles published from database inception through May 2021.We included randomized controlled trials (RCTs) comparing the addition of perioperative (post, pre, or both) systemic therapies to surgery alone in patients with CRLM. The outcomes were compared according to the chemotherapy regimen using a random effects model. Outcomes of interest included disease-free survival (DFS) and overall survival (OS). Results Seven RCTs with a total of 1504 patients with CRLM were included. Six studies included post-operative treatment and one evaluated perioperative (pre- and postoperative) therapy. Fluoropyrimidine-based chemotherapy was the most used systemic therapy. NMA showed benefit of adding perioperative therapy to surgery in terms of DFS (HR 0.73, 95% CI 0.63 to 0.84). However, these findings did not translate into a statistically significant OS benefit (HR 0.88, 95% CI 0.74 to 1.05). NMA did not show any advantage of one regimen over another including oxaliplatin or irinotecan. Conclusions This systematic review and NMA of 7 RCTs found that the addition of perioperative systemic treatment for resectable CRLM could improve disease-free survival but not overall survival. Based on the findings, addition of perioperative treatment in resectable CRLM should be individualized weighing the risks and benefits.
Background: Upfront docetaxel (UD) with androgen deprivation therapy (ADT) has been demonstrated to improve survival outcomes in metastatic castration-sensitive prostate cancer (mCSPC). However, existing studies have included predominantly Caucasian patients. Study Question: To compare the efficacy of addition of UD to ADT in mCSPC to ADT alone among minority patients. Study Design: Retrospective study of mCSPC patients. Measures and Outcomes: Patients treated with UD and ADT between January 2014 and December 2017 (UD + ADT, n = 44) were compared with those treated with ADT alone between January 2008 and January 2017 (ADT, n = 38); patients of Caucasian ethnicity were excluded. The outcome of interest was progression-free survival (PFS), which was estimated using Kaplan–Meier analysis and Cox proportional hazard analysis. Results: Overall, 63 (76.8%) patients were African American and 16 (19.5%) were Hispanic. Fifty-five (67%) patients had high-volume mCSPC. The median follow-up was 14 months [95% confidence interval (CI): 10.4–16.5] for UD + ADT and 42 months (95% CI: 17–66.9) for ADT. Median PFS did not differ between groups: UD + ADT: 16 versus ADT: 18 months [hazard ratio (HR) for UD + ADT = 0.88, 95% CI: 0.48–1.62; P = 0.70]. In patients with high-volume disease, median PFS remained similar (UD + ADT: 16 vs. ADT: 14 months (HR for UD + ADT = 0.64, 95% CI: 0.33–1.25; P = 0.19). On multivariable analysis, prolonged time to nadir PSA, HR = 0.83 (95% CI: 0.76–0.90), was independently associated with PFS. The most common toxicities in UD + ADT were anemia and fatigue. Major limitations include small sample size and potential for selection bias due to the retrospective study design. Conclusions: In this retrospective review of a minority mCSPC cohort, UD + ADT was not associated with improved PFS compared with ADT alone. Although further study with larger sample size is needed, these results underscore the importance of ensuring accrual of minorities in clinical trials, reflective of the real-world setting.
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